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Songbird Genome Yields Insight Into Vocal Communication

Researchers have identified more than 800 genes that appear to
play a role in the male zebra finch's ability to learn elaborate
songs from his father. A better understanding of the songbird's
communication may lead to insights into human communication.

Researchers have sequenced the genome of
the zebra finch. Photo courtesy of L. Brian Stauffer,
University of Illinois News Bureau

Only a few animals are known to communicate through learned vocalizations.
The male zebra finch (Taeniopygia guttata) learns complex
songs from his father, making the species a valuable model for
studying human speech, communication and neurological disorders.
At first, a fledgling finch makes seemingly random sounds, much
like the babble of human babies. With practice, the young bird
eventually learns to imitate his father's song. Once the bird has
mastered the family song, he will sing it for the rest of his life
and pass it on to the next generation. This ability to communicate
through learned vocalization is lacking in female zebra finches
and in chickens, the only other bird thus far to have its genome
sequenced.

The zebra finch genome sequence and analysis was published in
the April 1, 2010, issue of Nature. The research consortium
responsible was funded in part by NIH's National Human Genome Research
Institute (NHGRI) and led by Dr. Richard K. Wilson, director of
the Genome Center at Washington University School of Medicine in
St. Louis.

The researchers found that the chicken and zebra finch genomes
are similar in many ways. Both have about 1 billion DNA base pairs—roughly
one-third the size of the human genome. However, the analysis suggested
214 candidate genes that may be involved in the evolution of the
zebra finch’s unique vocal behavior. Of these, 49 are suppressed,
or turned off, in response to song. A disproportionately high number
in this group are ion channel genes. Ion channels allow the movement
of ions (electrically charged particles) across cell membranes.
Human ion channels have been shown to play key roles in many aspects
of behavior, neurological function and disease. The researchers
suspect that the evolution of this group of genes in songbirds
may be essential for learned vocalization.

The scientists also identified portions of the zebra finch genome
crucial to regulating the activity of genes involved in song behavior.
In particular, their analysis suggests that non-protein coding
ribonucleic acids (ncRNAs), which have been proposed to contribute
to the evolution of greater complexity in humans and other animals,
may be a driving force behind learned vocal communication.

"By comparing the finch genome with the human genome, we
should now be able to expand our understanding of learned vocalization
in humans. Such information may help researchers who are striving
to develop new ways to diagnose and treat communication disorders,
such as stuttering and autism," says NHGRI Director Dr. Eric
D. Green.

"Although scientists understand much about how songbirds
acquire and modify their vocal patterns, the availability of the
genome sequence will allow insight into the molecular underpinnings
of this natural behavior," says Dr. Story Landis, director
of NIH’s National Institute of Neurological Disorders and
Stroke (NINDS), which also provided support for the study. "This
could lead to better understanding of learning and memory, neural
development and adaptation, and speech and hearing disorders."